[C++] Tutorial 1: Discussion

eunhye732

This is my first time using a C++ program...actually any programs. my C++ programming class is a lot harder than my physics and math classes. =(
i've never struggled so much so i would REALLY REALLY appreciate as much help as possible. here is my problem:

Write a program that asks the user how many numbers will be entered and then has the user enter those numbers. When this is done, report to the user the position of the first 7 entered and the last 7 entered. By position we mean, for example, that if the first 7 is the 2nd number entered then its position would be 2.

Sample screen output 1:

How many numbers will be entered? 8
Enter num: 5
Enter num: 7
Enter num: 6
Enter num: 7
Enter num: 7
Enter num: 3
Enter num: 8
Enter num: 6
The first 7 was in position 2
The last 7 was in position 5

Sample screen output 2:

How many numbers will be entered? 8
Enter num: 5
Enter num: 2
Enter num: 6
Enter num: 7
Enter num: 1
Enter num: 3
Enter num: 8
Enter num: 6
The first 7 was in position 4
The last 7 was in position 4

Sample screen output 3:

How many numbers will be entered? 8
Enter num: 5
Enter num: 1
Enter num: 6
Enter num: 5
Enter num: 9
Enter num: 3
Enter num: 8
Enter num: 6
Sorry, no sevens were entered.

All i know is that for the counter controlled loop, I use the For loop and include the if-else statement inside the loop. I just can't get the problem to tell me the positions for both 7s.
thanks again.

eunhye732

if this was a wrong place to put my question, can you tell me where? Thanks

TenaliRaman

I will do it by keeping two variables,
1. min_pos - will hold the position of first 7
2. max_pos - will hold the position of last 7

Steps :
1. Initialise min_pos and max_pos to -1
2. Whenever a 7 is read,
if min_pos = -1, update min_pos = counter
if counter > max_pos, update max_pos = counter
3. if both min_pos = -1, output no 7 was read
otherwise output min_pos and max_pos

Once you are done with the program, read the program carefully. Try to understand how the value of -1 was being used here. Such techniques are commonplace in many programs, so it should help you out.

-- AI

scott1

I need help with tutorial.I'am working a assigment 1.I enterd this in the Bloodshed Dev C++.

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[]) {
    char myCharacter = 'z';
    cout << "The datatype is" << sizeof(int) << " bytes!" << endl;
    cout << " the varible has a value of " << myCharacter << endl;
    return 0;

}

It works kind of.For some starge reason the box pops up but it closes as soon as it opens.

dduardo

scott1, you can either run the application directly from thecommand line or add the following:

This should go at the top:

#include <cstdlib>

and this should go right before the return line:

system("PAUSE");

scott1

It works now.Thanks

scott1

I'am working on the Pythegrom therom assigment.I need help

Code:

#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[]) {
  int a = 'a', b = 'b', c = 'c';
     cout << "Enter Length of A" << endl;
     cin >>  a;
     cout << "enter length of b" << endl;
     cin >> b;
  a * a * b * b == c * c
   cout  << "c =" <<  c << endl;
    system("PAUSE");
    return EXIT_SUCCESS

It says there somthing worng with line 13 and 4 things with line 15 but I think there's probally more stuff worng with it then that.

dduardo

Why are you doing a = 'a', b='b', c='c'?

Why don't you just do: double a, b, c;

Then the pythagorean theorem is simply c = sqrt(a*a+b*b) ;

remember to #include <cmath> for the sqrt function.

scott1

It worked thanks

scott1

Is there ever going to be another more advance tutoril

JamesU

I've dont this before and now I'm trying to do the hypotenuse thing again...here's what I've got:

Code:

#include <cstdlib>
#include <iostream>
#include <cmath>

using namespace std;

int main(int argc, char *argv[])
{
   double a, b, c;
   
   a = sqrt(b*b+c*c);
   
   cin >> b >> c;
   cout << a;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

every time I run it a is equal to 0 EDIT: I'm stupid, I got it..

scott1

I the "cin" needs to go before the equation.

longdh

I have an exercise of building matrix class with characters: plus, subtract, divide, convert. Can you help me?

cworrier

I suppose I may have posted this out of place, but it seemed to go beyond the tutorial. Here it is again.

I've been trying for days to get my boyfriend's C++ program to work, and I am almost ready to concede defeat, but I have frequented this site in the past as a lurker, actually learning a lot of what I know from the tutorials (thanks!).

Now, I have a problem I just can't seem to solve.

The object is to have the user pick a choose from a menu and have that value stored somewhere to be used by a function later. Once that choice is picked, the user needs to be able to pick another choice, until he or she fills in all three choices and then it's on to the formula! I also need a choice for clearing the data (I know how to set it all to 0) and one for quitting the program (just return 0; right?), as well as a display of the data that has been entered already once the formula calculates (I have this block of code written too). My formula works, but I'm not sure how to get all the values stored or how to let the user go back and pick a choice from the list after he or she has chosen one already.

Here's what I have so far, and it's a work in progress, but hopefully it's on the right track. I'm thinking I need to, maybe, use a switch statement for the menu, but I can't get that to work for me, and I'm still not sure how to store a value that's not going to be immediately used (maybe something with an array, but again I seem unable to produce the right code).

#include <iostream>
#include <math.h>
using namespace std;

doublemortgage (int c, double b, double a)
{
int i = c;
double j = b;
double k = a;
double l = b/(12 * 100);
double m = c * 12;
double result = k * (l / (1 - pow(1+l, -m)));
return result;
}

int main ()
{
int c;
double b;
double a;
double result;
int x;

cout << "Mortgage Calculation Menu \n";
cout << "1. Enter a Loan Amount \n";
cout << "2. Enter a Loan Rate \n";
cout << "3. Enter a Term in Years \n";
cout << "4. Calculate a Payment \n";
cout << "5. Clear All Input \n";
cout << "9. Quit \n";
cout << "Enter Your Selection: ";
cin >> x;

cout << " \n";

cout << "Enter a Loan Amount: $";
cin >> a;
cout << "Enter a Loan Rate: ";
cin >> b;
cout << "Enter a Term in Years: ";
cin >> c;
cout << "Your Monthly Payment: $"<< mortgage(c, b, a) << endl;

cout << " \n";

cout << "You Entered" << endl;
cout << "Loan Amount: $" << a << endl;
cout << "Loan Rate: " << b << "%" << endl;
cout << "Loan Term: " << c << "years" << endl;
cout << "Monthly Payment: $" << mortgage (c, b, a) << endl;

return0;
}

Randeh

Is there a version of the getSubString function in c++? If so, what is it and what are the parameters?

-Thanks in advance

Freelancer

alright, so im an Electrical Engineering major, and my current project requires me to program....
im using Visual STudio 2005, and im having a little trouble with just the basics...

here's my program so far:

#include <iostream.h>
#include <stdio.h>
#include <stdlib.h>

int main
{
printf("heuy");
cout<< "hey";

return 0;

}

i run it, and all it gives me is a blank window....
it doesnt write anything....
can anyone help me?

neurocomp2003

mmm ....did tha tcode actually compile???
my guess would be that your main call is missing something.

if it closes to fast put a pause statement like delay, getch, getchar.

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eunhye732	if this was a wrong place to put my question, can you tell me where? Thanks

dduardo Recognitions: Staff Emeritus	scott1, you can either run the application directly from thecommand line or add the following: This should go at the top: #include <cstdlib> and this should go right before the return line: system("PAUSE");

scott1	Is there ever going to be another more advance tutoril

longdh	I have an exercise of building matrix class with characters: plus, subtract, divide, convert. Can you help me?

Randeh	Is there a version of the getSubString function in c++? If so, what is it and what are the parameters? -Thanks in advance

neurocomp2003	mmm ....did tha tcode actually compile??? my guess would be that your main call is missing something. if it closes to fast put a pause statement like delay, getch, getchar.